Solar distillation device

ABSTRACT

A solar distillation apparatus utilizing a substantially vertical reactor assembly is disclosed. The reactor consists of a tubular outer shell, a base, a cap, and a central tension member. The annular space between the outer tube and the central tension member forms the reactor chamber. Seawater or other feed liquid enters the reactor chamber through the base plate. Reflected or direct solar energy heats the feed liquid, generating low pressure vapor. The vapor exits the reactor through the cap structure or the base. The concentrate left behind settles by gravity to the bottom region of the reactor&#39;s liquid column. Extension tubes on the feed openings allow feed liquid to enter the liquid column above the concentrate layer and avoid excessive mixing of the feed liquid and the concentrate. The concentrate exits the reactor through one or more openings in the base.

BACKGROUND

1. Field of the Invention

This invention relates generally to the field of solar energy andsystems, particularly to distillation of liquids by utilizing solarradiation.

2. Discussion of Prior Art

All publications herein are incorporated by reference to the same extentas if each individual publication or patent application was specificallyand individually indicated to be incorporated by reference. Thefollowing description includes information that may be useful inunderstanding the present invention. It is not an admission that any ofthe information provided herein is prior art or relevant to thepresently claimed invention, or that any publication specifically orimplicitly referenced is prior art.

As the cost of fossil fuels increases and the scarcity of potable waterbecomes more acute, the need for alternative methods of freshwaterproduction becomes greater each year. In fact, much of the developingworld's population lives where potable water is extremely rare.Therefore, an easily manufactured, simply operated means for producingfresh water from brackish water would be a critical step in providingthe basic necessities of life for literally millions of people. Solardistillation is perhaps the most basic method for generating potablewater from seawater or brackish water, and simple solar distillationsystems have been in use in one form or another for hundreds of years.

Several issued U.S. patents specifically relate to machines that use thesun's energy to evaporate seawater in a closed reactor. The steam vaporgenerated rises above the water surface and condenses on the insidecover of the reactor. The distillate collected is suitable as potablewater. Examples of “solar stills” can be found in U.S. Pat. No.6,767,433 (Foster et al. 2004), U.S. Pat. No. 6,001,222 (Klein 1999),U.S. Pat. No. 4,235,678 (McKeen 1980), and U.S. Pat. No. 4,135,985(LaRocca 1979). These devices, ranging in size from personal fresh watergenerators to building-sized units, generally involve an insulated box,a pan or pool of water, and a transparent top that allows light to enterbut traps heat and vapor.

Numerous improvements have been developed to increase the efficiency ofsuch devices, including lowering the air pressure above the watersurface (thereby lowering the amount of heat required for generatingvapor), using forced or induced ventilation to increase evaporationrates, using cover “shakers” to help condensed water migrate down thecover to the collection trough, and separating the evaporation chamberfrom the condensation chamber to increase thermal efficiency. Floatingunits have been patented that utilize the ocean or lake as a heat sinkfor the condenser, see, for example, U.S. Pat. No. 6,656,326 (Nagler2003). Because these devices rely on direct solar heating, theireffectiveness is limited by the size of the device.

Another broad class of inventions utilizes inclined or horizontal tubesfor the evaporation chamber. The tubes are located at the focal point orfocal line of a reflector, or in some cases, they are located at thefocal point of a Fresnel lens. Examples of these devices can be found inU.S. Pat. No. 5,505,917 (Collier 1996), U.S. Pat. No. 5,191,876 (Atchley1993), and 4,312,709 (Stark et al. 1982). U.S. Pat. No. 2,141,330 (Abbot1938) shows an early solar distilling apparatus that uses a clockworkmechanism to track the sun's path through the sky. In this and similardevices, the fluid is heated as it travels through the tubing, similarto a conventional boiler. The steam generated can be used for work, heattransfer, heat storage, or, if conveyed to a condenser, the steam can bereturned to liquid distillate. Unfortunately, these devices aresusceptible to mineral (scale) buildup in the evaporation tubes. Thiscan be partially overcome by the use of a closed heating circuit with anengineered working fluid, but this solution adds another level ofcomplexity and additional heat transfer loss between loops.

Vertical arrangements for solar evaporators are less numerous. Onearrangement is shown as part of a larger system in U.S. Pat. No.4,373,996 (Maruko 1983). Vertical distillation towers for alcohol havebeen patented, e.g. U.S. Pat. No. 4,377,441 (Kimmell 1983), U.S. Pat.No. 4,455,374 (Schwarz 1984), and U.S. Pat. No. 102,633 (Wheeler et al.1870). The '441 patent shows a solar distilling apparatus with avertical reactor and automated fill and relief valves. The design showsa parabolic reflector arranged to focus sunlight onto the bulbous“boiler” section of the reactor. This design shows one advantage of avertical reactor arrangement, that of compact size, but it also showsthe difficulty in supporting the reactor column at sizes larger thandesktop units. In addition, the device uses complex valves to maintainsuitable fluid levels and temperatures within the boiler and distillingtower.

Providing a cost-effective and workable method to separate the raw feedliquid from the concentrated liquid left behind after the vapor has beendriven off is a problem common to all previous designs. Batch modeoperation is one method, but that solution eliminates continuousproduction and potentially wastes part of the daily sun cycle.

Therefore, there is a need in the art for a simple, cost-effective andeasily manufactured device that can be employed to desalinate, purify,or distill water or other liquids.

SUMMARY

The following embodiments and aspects thereof are described andillustrated in conjunction with apparatuses and methods which are meantto be exemplary and illustrative, not limiting in scope.

The present invention includes a machine, apparatuses, and methods forevaporating liquid to create distillate and concentrate utilizing solarradiation.

Various embodiments provide for a machine comprising a substantiallyvertical, tubular evaporation reactor adapted to provide a liquidconcentrate region below a feed liquid region, a base located at a lowerend of said evaporation reactor, a cap structure located at an upper endof said evaporation reactor, a means for feed liquid to enter said feedliquid region within said evaporation reactor, a means for liquidconcentrate to exit said evaporation reactor from said liquidconcentrate region, a means for vapor to exit said evaporation reactor,and at least one tension member that connects said base to said capstructure and which is adapted to compress said evaporation reactorbetween said base and said cap structure, thereby creating substantiallywatertight seals between said base, said evaporation reactor, and saidcap structure.

The machine may further include at least one solar reflector devicelocated in relation to said evaporation reactor so as to directreflected solar radiation to a point or line coincident with saidevaporation reactor.

In another embodiment, said evaporation reactor may comprise an outertube and an inner tube of smaller outside dimension relative to saidouter tube located concentrically within said outer tube, whereby saidouter tube and said inner tube form a longitudinal annulus adapted for afeed liquid to react with solar radiation. Said outer tube may besubstantially transparent, and may further include small diameter wireembedded within and/or affixed to the surface of said outer tube. Saidinner tube and/or said outer tube may be tinted blue-green to resemblethe color of water in the ocean.

In another embodiment, said tension member may comprise at least onerod, affixed to and extending from said base to said cap structure, saidrod affixed to said cap structure, said rod adapted to be put in tensionwhereby said evaporation reactor is in compression.

In another embodiment, said tension member may comprise at least oneflexible, elastic member secured to said base and to said cap structure,said elastic member adapted to act in tension to compress saidevaporation reactor between said base and said cap structure.

In another embodiment, said evaporation reactor may comprise asubstantially transparent outer tube and said tension member maycomprise at least one rod extending from said base to said capstructure, said rod adapted to act in tension to compress saidevaporation reactor between said base and said cap structure.

In another embodiment, said means for liquid concentrate to exit saidevaporation reactor may comprise at least one concentrate exit port insaid base located within the area circumscribed by said evaporationreactor, each of said at least one concentrate exit port adapted to actas a passageway for liquid concentrate to exit said evaporation reactor.This embodiment may further include a liquid concentrate meteringdevice, wherein said liquid concentrate exit port is hydraulicallyconnected to said metering device to regulate concentrate flow from zeroto a predetermined maximum flow rate.

In another embodiment, said means for feed liquid to enter said feedliquid region may comprise at least one feed liquid entry port in saidbase located within the area circumscribed by said evaporation reactorand at least one tubular extension fit to each of said at least one feedliquid entry port on an upper surface of said base, wherein saidextension terminates in said feed liquid region, and whereby sucharrangement allows the feed liquid to remain substantially separatedfrom the liquid concentrate. This embodiment may further include a feedliquid tank, wherein said feed liquid entry port is hydraulicallyconnected to said feed liquid tank, said feed liquid tank located suchthat a predetermined liquid surface operating level is maintained withinsaid tubular evaporation reactor by gravity flow.

In another embodiment said means for vapor to exit comprises a vaporexit port in said cap structure and a vapor conduit fit to said capstructure.

In another embodiment, said means for vapor to exit comprises a vaporexit port in said base and a vapor conduit fit to said base, said vaporconduit extending upwards to a point above the liquid surface insidesaid evaporation reactor.

Other embodiments of the present invention provide for methods ofcreating distilled liquid from contaminated liquids using solarradiation. In one embodiment, the method comprises providing a machineof the type comprising a substantially vertical, tubular evaporationreactor adapted to provide a liquid concentrate region below a feedliquid region, a base located at a lower end of said evaporationreactor, a cap structure located at an upper end of said evaporationreactor, a means for feed liquid to enter said evaporation reactor insaid feed liquid region, a means for liquid concentrate to exit saidevaporation reactor from said liquid concentrate region, a means forvapor to exit said evaporation reactor, at least one tension member thatconnects said base to said cap structure and acts to compress saidevaporation reactor between said base and said cap structure, therebycreating substantially watertight seals between said base, saidevaporation reactor, and said cap structure; providing at least onesolar reflector device located congruently with said evaporation reactorso as to direct reflected solar radiation to a point or line coincidentwith said evaporation reactor; introducing feed liquid into saidevaporation reactor; and drawing off distillate. This method may furthercomprise recovering, with a suitable heat exchanger, heat lost throughcondensation of said vapor and/or heat transported with the concentrate,and using said recovered heat to preheat feed liquid.

Other embodiments of the present invention provide a machine forevaporating liquids, comprising a substantially vertical, tubularevaporation reactor adapted to provide a liquid concentrate region belowa feed liquid region, a base located at a lower end of said evaporationreactor, a cap structure located at an upper end of said evaporationreactor, at least one feed liquid opening in said base located withinthe area circumscribed by said evaporation reactor and at least onetubular extension fit to each of said at least one feed liquid openingon an upper surface of said base, wherein said extension terminates insaid feed liquid region, and whereby such arrangement allows the feedliquid to remain substantially separated from the liquid concentrate, atleast one concentrate opening in said base located within the areacircumscribed by said evaporation reactor, each said concentrate openingadapted to act as a passageway for liquid concentrate to exit saidevaporation reactor, at least one vapor opening in said cap structure,in said base, or both and at least one vapor conduit hydraulicallyconnected to said opening, and at least one tension member that connectssaid base to said cap structure and which is adapted to compress saidevaporation reactor between said base and said cap structure, therebycreating substantially watertight seals between said base, saidevaporation reactor, and said cap structure.

The machine may further include at least one solar reflector devicelocated in relation to said evaporation reactor so as to directreflected solar radiation to a point or line coincident with saidevaporation reactor.

In another embodiment, said evaporation reactor may comprise an outertube and an inner tube of smaller outside dimension relative to saidouter tube located concentrically within said outer tube, whereby saidouter tube and said inner tube form a longitudinal annulus adapted for afeed liquid to react with solar radiation. Said outer tube may besubstantially transparent, further including small diameter wireembedded within and/or affixed to the surface of said outer tube. Inanother embodiment, said inner tube and/or said outer tube may be tintedblue-green to resemble the color of water in the ocean.

In another embodiment, said tension member may comprise at least onerod, affixed to and extending from said base to said cap structure, saidrod affixed to said cap structure, said rod adapted to be put in tensionwhereby said evaporation reactor is in compression.

In another embodiment said tension member may comprise at least oneflexible, elastic member secured to said base and to said cap structure,said elastic member adapted to act in tension to compress saidevaporation reactor between said base and said cap structure.

In another embodiment, said evaporation reactor may comprise asubstantially transparent outer tube and said tension member maycomprise at least one rod extending from said base to said capstructure, said rod adapted to act in tension to compress saidevaporation reactor between said base and said cap structure.

Another embodiment may further include a liquid concentrate meteringdevice, wherein said liquid concentrate opening is hydraulicallyconnected to said metering device to regulate concentrate flow from zeroto a predetermined maximum flow rate.

Another embodiment may further include a feed liquid tank, wherein saidfeed liquid opening is hydraulically connected to said feed liquid tank,said feed liquid tank located such that a predetermined liquid surfaceoperating level is maintained within said tubular evaporation reactor bygravity flow.

Other features and advantages of the invention will become apparent fromthe following detailed description, taken in conjunction with theaccompanying drawings, which illustrate, by way of example, variousfeatures of embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments are illustrated in the referenced figures. It isintended that the embodiments and figures disclosed herein are to beconsidered illustrative rather than restrictive.

FIG. 1 is an isometric view showing a reactor and reflector system sizedfor individual or family use in accordance with an embodiment of thepresent invention.

FIG. 2 is a detailed section view of a connection between the capstructure, tension member, and tubular reactor in accordance with anembodiment of the invention.

FIG. 3 is a detailed section view of a connection between the base,tension member, and tubular reactor in accordance with an embodiment ofthe invention.

FIG. 4 is a section view of an automated system in accordance with anembodiment of the invention.

FIG. 5 is an isometric view of an outer cylinder with embedded wires inaccordance with an embodiment of the invention.

FIG. 6 shows an elevation of a large-scale system utilizing an array ofreflectors and components sized for greater production volumes inaccordance with an embodiment of the invention.

FIG. 7 is a section view of an alternate reactor construction methodomitting the separate inner cylinder in accordance with an embodiment ofthe invention.

FIGS. 8, 8B and 8C are detail views of an alternate, elastic tensionmember in accordance with an embodiment of the invention.

FIG. 9 shows an alternate reactor where vapor exits the reactor throughthe base rather than the cap structure in accordance with an embodimentof the invention.

FIG. 10 is a system schematic and flow diagram, in accordance with anembodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

All references cited herein are incorporated by reference in theirentirety as though fully set forth. Unless defined otherwise, technicaland scientific terms used herein have the same meaning as commonlyunderstood by one of ordinary skill in the art to which this inventionbelongs.

One skilled in the art will recognize many methods and materials similaror equivalent to those described herein, which could be used in thepractice of the present invention. Indeed, the present invention is inno way limited to the methods and materials described.

The invention is designed to use direct and/or reflected solar radiationto heat liquid until it evaporates, producing low pressure vapor. Thegeneral arrangement consists of a tubular, substantially verticalreactor in which a column of liquid is heated by the sun's direct orreflected energy. The phrase “substantially vertical” is defined as theallowable deviation from vertically plumb, established through routineexperimentation for each embodiment of the invention, that will createthe desired liquid feed and liquid concentrate regions within thereactor as described more fully below. The reactor has a cap structureand a base. A tension member creates a substantially watertight reactorassembly by putting the reactor tube into compression between the capand the base.

As the liquid is heated, vapor is driven off at the top of the watercolumn. A conduit conveys the vapor out of the reactor column where itcan then be condensed to form distilled liquid. Inside the reactor, theliquid left behind, termed concentrate throughout this document, is moredense than the incoming feed liquid because it contains material leftbehind by the evaporated liquid. The material may include mineral salts,organics, suspended solids, particulates, or other compositions that donot travel with the vapor. The concentrate tends to settle by gravity tothe lower portions of the reactor. This area is termed the liquidconcentrate region of the reactor. The region extends up from the base adistance that may be determined by routine experimentation based on agiven reactor size, a given feed liquid, and a given desired contaminantlevel in the concentrate. Concentrate may exit the reactor throughopenings in the base.

The feed liquid may be introduced into the liquid column inside thereactor at a point above the liquid concentrate region. The feed liquidcan flow through additional openings in the base and up into tubes orpipes that extend above the base surface. By this arrangement, mixingbetween the exiting concentrate and incoming feed liquid issubstantially reduced. The area where the feed liquid enters the liquidcolumn inside the reactor is termed the feed liquid region.

Low pressure vapor from the reactor is conveyed to a condenser where itreturns to a liquid state. This liquid distillate may be suitable forconsumption, further treatment, or disposal, depending on the feedliquid.

The concentrate may be conveyed from the reactor for treatment, disposalor other uses depending on the feed liquid. In some uses, creating theconcentrate may be the primary function of the device, for example, ifthe device is used to thicken the feed liquid or to drive off volatilecomponents of the feed liquid. Thus, the device may be useful inapplications such as stripping volatile organic compounds or petroleumcontaminants.

The reader will note that the invention described above operates with nomoving parts, and no membrane or partition is required to separate theliquid concentrate region from the feed liquid region.

With the addition of an adjustable valve to regulate the flow ofconcentrate, the system can operate continuously in accordance withavailable sunlight, feed liquid characteristics, geographical location,desired concentrate density, and other factors that may impactperformance.

The feed liquid would be conveyed from a source that incorporates anarrangement or mechanism to maintain a constant liquid level inside thereactor. This level could vary with the factors described above, but mayallow for a vapor space in the reactor above the liquid column to occupyfrom zero percent to sixty percent of the total reactor length. Themechanism to maintain a constant level could be an elevated tank andgravity flow, or a level sensing instrument and control valve, or othercommon control elements.

A small system could operate without electric motors or controls. Such asystem may consist of a manual throttling valve, an elevated tank offeed liquid, and a simple coiled tube for condensing the vapor. Oncepositioned properly, such a system would operate with only human-poweredcontrol, such as adjusting the concentrate regulating valve, filling thefeed tank and/or the reactor, and positioning the reactor. Conversely,the system could be made more complex to include features such as amoving reflector with a sun tracking device, motorized inlet and outletvalves, and instrumentation to control the outlet valve based oncontaminant levels in the concentrate. Photovoltaic panels and batteriescould eliminate or reduce such a system's dependence on grid power. Theinvention is scalable both in individual reactor size and in number ofreactor units. In a large scale application, the reactor tower could bemany feet tall, and an array of multiple reflectors would be used todirect solar radiation to the tower.

EXAMPLE 1

In a first exemplary embodiment, as shown in FIG. 1, the solardistillation device consists of evaporation reactor 1 centered inparabolic reflective dish 2, feed tank 18, condenser 23, and variousconnecting pipes or conduits described further below. The components ofevaporation reactor 1 include outer cylinder 3, inner cylinder 4 locatedconcentrically to outer cylinder 3, base 5, cap structure 6, andthreaded rod 7. Outer cylinder 3 may be constructed of thin-walledglass. Inner cylinder 4 may also be constructed of glass, and in thisembodiment is thicker walled. In various embodiments, the outercylinder's wall thickness could be three-eighths (⅜) of an inch, and theoutside diameter could be twelve (12) inches. The inner cylinder's wallthickness could be three (3) inches, and the outside diameter could beeight (8) inches. The cylinders could be approximately seven (7) feettall in such an embodiment.

The annular space between outer cylinder 3 and inner cylinder 4 createsa hollow, cylindrical volume wherein the liquid is heated. Base 5 sealsthe bottom of the reactor, and cap structure 6 seals the top of theunit. In this embodiment, the base and cap are constructed of anon-corrosive or suitably coated metallic material, but other materials,such as plastics, ceramics, or glass could also be used. In thisembodiment, the cap is dome-shaped and the base is a flat plate, but theshapes of both can be varied. A tension member, in this case threadedrod 7, extends longitudinally from base 5 to cap structure 6, throughthe center of inner cylinder 4, and ties the reactor assembly together.In this embodiment, the threaded rod may be one (1) inch nominal outsidediameter and constructed of stainless steel. This arrangement creates astrong, easily manufactured reactor assembly that is substantiallywatertight.

FIG. 2, a detail enlargement of FIG. 1, shows threaded rod 7, tensioningnut 11, cap structure 6, outer cylinder 3, and inner cylinder 4 insection view. When tensioning nut 11 is tightened against cap structure6, threaded rod 7 pulls base 5 and cap structure 6 against the ends ofreactor cylinders. Depending on the materials used for the reactorcomponents, optional top sealing gaskets 12 a and 12 b may be needed tocreate a substantially watertight seal between the cylinders and the capstructure. One skilled in the art will recognize that the threaded rodcan be placed in tension by methods other than a tensioning nut, andindeed, the threaded rod may be replaced by other structures capable ofacting in tension. Cap structure 6 is shown with vapor opening 24, towhich vapor conduit 10 is attached. Vapor conduit 10 connects tocondenser 23, as shown in FIG. 1.

FIG. 3, also a detail enlargement of FIG. 1, shows base 5, threaded rod7, outer cylinder 3, and inner cylinder 4 in greater detail. Dependingon the materials used for the reactor components, optional bottomsealing gaskets 13 a and 13 b may be used to create a substantiallywatertight seal between the cylinders and the base structure.

As also shown in FIG. 3, base 5 is equipped with feed liquid openings14, feed liquid extensions 15, and concentrate openings 16. Feed liquidextensions 15 extend up from the base, terminating at inlet feed point17 located in the feed liquid region of the reactor's liquid column. Inthis embodiment, the feed liquid region could consist of the upperthirty (30) to eighty (80) percent of the liquid column depth, while theliquid concentrate region could consist of the lower twenty (20) toseventy (70) percent of the liquid column depth.

Referring again to FIG. 1, base 5 is attached to feed pipe 8 that alsoconnects to feed tank 18. Feed pipe 8 may be equipped with optionalvalve 19 that serves to control feed liquid flow from feed tank 18 toreactor 1. In this embodiment, feed tank 18 is equipped with float valve20 that regulates flow from the feed source 21.

Base 5 is also attached to concentrate conduit 9. Concentrate conduit 9is connected to concentrate throttling valve 22 that controls theconcentrate flow rate.

In a simple, manual mode of operation, reflective dish 2 is positionedso as to take fullest advantage of the sun's rays. Feed source 21 isconnected to feed tank 18, and brackish water, sea water, or othercontaminated liquid (collectively, feed liquid) enters the feed liquidregion of the annular reactor space through feed liquid openings 14 andextensions 15 in base 5. Concentrate throttling valve 22 is closedinitially.

Sunlight reflected from reflective dish 2 heats the liquid column in thereactor. As the liquid column is heated and begins to evaporate, lowpressure vapor collects at the top of the reactor under cap 6 and isconducted away from the reactor via vapor conduit 10. The low pressurevapor is returned to liquid distillate in any suitable, commerciallyavailable condenser 23. In small units, the condenser may be omitted,because the vapor conduit would be long enough to condense the vaporwithin its length. Heat rejected by the condensation of vapor to liquidcan be recovered in the feed water through the use of a suitablecondensing heat exchanger.

The liquid left behind in the reactor after partial evaporation (theconcentrate) has a higher concentration of dissolved salts, solids, orother contaminants than the incoming feed liquid, and thus is more densethan the incoming feed liquid. The concentrate settles by gravity to theliquid concentrate region near the surface of base S. After evaporationstarts, concentrate valve 22 is opened and adjusted so that liquidconcentrate leaves the reactor through concentrate openings 16 at a ratesufficient to optimize vapor generation but minimize scale buildup.Concentrate conduit 9 conveys the concentrate away from the reactor forfurther processing or disposal. In alternate embodiments, theconcentrate heat can be recovered through the use of a suitable,commercially available heat exchanger. The heat can be transferred tothe feed liquid to improve thermal efficiency of the system or used forother purposes.

Feed liquid enters the reactor automatically (by gravity in thisembodiment) as vapor is driven off and concentrate is released from thereactor column. Feed liquid is supplied from feed tank 18 which servesto maintain a constant liquid level in the reactor. Feed tank 18 isfilled via float valve 20 which regulates inlet flow from the feedsource 21. In alternate embodiments, the feed tank may be equipped witha tank heater wherein heat can be transferred from distillate orconcentrate to the liquid pool.

EXAMPLE 2

FIG. 4 shows an example of the solar distillation device using the samebasic concept of the evaporation reactor, but utilizing auxiliaryequipment such as a moving reflector 40 with a drive mechanism 41 usedto drive the reflector and track the sun's path across the sky. In FIG.4, the concentrate valve 42 is automated. Based on operating data, anoptimum concentrate flow can be generated by routine experimentation,and concentrate valve 42 can be modulated automatically in accordancewith the contaminant concentration. Instrument 43 is used to measure theconcentrate contaminate level through resistance, density, particlecount, or other methodology as readily appreciated by someone skilled inthe art.

Additionally, FIG. 4 shows automated feed valve 44, whereby the liquidlevel in reactor 45 is maintained by modulating feed valve 44, suchmodulations being based on level controller 46 output. Level controller46 is any suitable instrument that monitors liquid level based on anultrasonic signal, pressure signal, electro-resistance or othermethodology. In this embodiment, feed tank 18 of FIG. 1 is replaced byany suitably pressurized feed source. Through such additions to thebasic device of FIG. 1, the distillation system can be made to operateautomatically for extended periods without human interaction afterinitial startup.

EXAMPLE 3

FIG. 5 shows an embodiment utilizing a glass outer cylinder thatincludes metal wire 51 embedded within or affixed to the glass similarto shatterproof or security glass. The wire embedded in the outsidecylinder can be arranged to act as an electric heating element tomaintaining the water column temperature overnight, during overcastperiods, or at other periods when auxiliary heating is advantageous.

EXAMPLE 4

FIG. 6 shows an embodiment on a larger scale, where base 5 of FIG. 1 hasbeen replaced by a constructed base deck 61 that may be made, forexample, of cast-in-place or precast concrete, and the reflective dish 2of FIG. 1 has been replaced by the array 62 of multiple reflectors, eachfocusing its rays on the central evaporation reactor 63. The reactorfunctions and is constructed on the same principle as the smaller unitof the first embodiment, but the size of the system components would bescaled accordingly.

EXAMPLE 5

FIG. 7 shows an embodiment wherein inner cylinder 4 of FIG. 1 has beeneliminated. In lieu of the inner cylinder, threaded rod 7 of FIG. 1 hasbeen modified to tension member 71 of this FIG. 7 that provides anappropriately sized annular space for the liquid column in theevaporation reactor. Tension member 71 functions similarly to threadedrod 7, but would require machining or special fabrication as compared tothe embodiment of FIG. 1.

EXAMPLE 6

FIGS. 8A, 8B, and 8C show an alternative tension cord 81, where in lieuof a threaded rod, a flexible, elastic material (such as rubber tubing,shock cord or “bungee” cord) is used as the tensioning member. Thefigures show various methods for applying tension to tension cord 81,including a pin-and-loop arrangement 82, a hook and thimble 83, and asnap-over cam 84.

EXAMPLE 7

FIG. 9 shows an alternative reactor arrangement where the vapor exitsthe reactor via vapor openings 92 in base 91. Vapor extension 93 is fitto base 91 and extends to a point above the liquid surface inside thereactor. Such arrangement would eliminate the vapor openings 24 in capstructure 6 shown in FIG. 1.

EXAMPLE 8

FIG. 10 shows a flow diagram of the process as well as optionalcomponents that could be incorporated to the basic processes describedabove to improve thermal efficiency of the system. These componentscould include a feed liquid/liquid concentrate heat exchanger, a feedtank heater, a feed liquid/vapor condensing heat exchanger, or a feedliquid/distillate heat exchanger. Feed liquid is introduced to system100. Level control device 105 allows feed liquid to enter reactor 110only as needed to maintain a nearly constant operating level. Feedliquid enters the feed liquid region 140 within reactor 110 and isheated by heat source 115. Feed liquid partially evaporates. Vapor exitsreactor 110 and is condensed back to liquid distillate 120. Liquiddistillate 120 exits system 100 for further use, treatment, or disposal.Concentrate settles towards bottom of reactor, creating liquidconcentrate region 130. Concentrate control valve 135 regulates liquidconcentrate flow out of the reactor. Concentrate exits reactor 110through concentrate control valve 135. Concentrate exits system 100 forfurther treatment, disposal, or other uses. Vapor/feed liquid condensingheat exchanger 150 may be used to transfer heat of condensation fromvapor to feed liquid. The distillate can also be routed throughdistillate/feed liquid heat exchanger 170 for further heat transfer.Similarly, liquid concentrate/feed liquid heat exchanger 160 may be usedto transfer heat from exiting concentrate to incoming feed liquid.Finally, concentrate or distillate could be routed through feed tankheater 190 which would transfer heat into the liquid pool inside tank180. Such additional heat exchangers function to increase the thermalefficiency of the system.

At least one embodiment of the solar distillation device provides anefficient, easily manufactured device that can operate for extendedperiods with little or no human intervention. Because the basic designof the reactor works in small and large scales, variations of the devicecan be built for a wide range of production flows. In addition, byutilizing multiple reactors, systems can be built which provide bothincreased production capability and redundancy.

While the above description contains many specific details, these shouldnot be construed as limitations on the scope of the invention, butrather as exemplaries of several preferred embodiments. Many variationsof the reactor design are possible, but have been omitted from thedrawings as less important to the function of the device.

For example, the reactor tube could be transparent or opaque, and couldbe tinted various shades of blue, blue-green, or green to take on thecolor of the ocean, thereby potentially increasing the efficiency of thedevice.

Additionally, the reactor tube cross-section can be of any shape inaddition to cylindrical, for example rectangular, triangular, oval, orpolygonal. Furthermore, besides glass, the reactor tubes can be of anymaterial of sufficient strength and transparency and suitable thermalproperties, for example, polycarbonate, Pyrex®, or other materials. Inaddition, transparent reactor tubes could be replaced by a thin-shelled,metallic tube tinted a dark color to take advantage of direct thermalheating.

The tension member connections to either or both the base and the capstructure can be made with other means besides a tensioning nut onthreads, including but not limited to elastic fabric, rubber or shockcord connections, internal threads on the cap and/or base plate and ortension rod itself, magnetic or electromagnetic connections,turnbuckles, wedges, cams, or other means of applying tension to thetension rod and compressing the outer cylinder.

Accordingly, the scope of the invention should be determined not by theembodiments illustrated, but by the appended claims and their legalequivalents.

1. A machine for evaporating liquids, comprising: (a) a substantiallyvertical, tubular evaporation reactor adapted to provide a liquidconcentrate region below a feed liquid region, (b) a base located at alower end of said evaporation reactor, (c) a cap structure located at anupper end of said evaporation reactor, (d) a means for feed liquid toenter said feed liquid region within said evaporation reactor, (e) ameans for liquid concentrate to exit said evaporation reactor from saidliquid concentrate region, (f) a means for vapor to exit saidevaporation reactor, and (g) at least one tension member that connectssaid base to said cap structure and which is adapted to compress saidevaporation reactor between said base and said cap structure, therebycreating substantially watertight seals between said base, saidevaporation reactor, and said cap structure.
 2. The machine of claim 1,further including at least one solar reflector device located inrelation to said evaporation reactor so as to direct reflected solarradiation to a point or line coincident with said evaporation reactor.3. The machine of claim 1 wherein said evaporation reactor comprises anouter tube and an inner tube of smaller outside dimension relative tosaid outer tube located concentrically within said outer tube, wherebysaid outer tube and said inner tube form a longitudinal annulus adaptedfor a feed liquid to react with solar radiation.
 4. The machine of claim3 wherein said outer tube is substantially transparent, furtherincluding small diameter wire embedded within and/or affixed to thesurface of said outer tube.
 5. The machine of claim 3 wherein said innertube and/or said outer tube is tinted blue-green to resemble the colorof water in the ocean.
 6. The machine of claim 1 wherein said tensionmember comprises at least one rod, affixed to and extending from saidbase to said cap structure, said rod affixed to said cap structure, saidrod adapted to be put in tension whereby said evaporation reactor is incompression.
 7. The machine of claim 1 wherein said tension membercomprises at least one flexible, elastic member secured to said base andto said cap structure, said elastic member adapted to act in tension tocompress said evaporation reactor between said base and said capstructure.
 8. The machine of claim 1 wherein said evaporation reactorcomprises a substantially transparent outer tube and said tension membercomprises at least one rod extending from said base to said capstructure, said rod adapted to act in tension to compress saidevaporation reactor between said base and said cap structure.
 9. Themachine of claim 1 wherein said means for liquid concentrate to exitsaid evaporation reactor comprises at least one concentrate exit port insaid base located within the area circumscribed by said evaporationreactor, said concentrate exit port adapted to act as a passageway forliquid concentrate to exit said evaporation reactor.
 10. The machine ofclaim 9, further including a liquid concentrate metering device, whereinsaid liquid concentrate exit port is hydraulically connected to saidmetering device to regulate concentrate flow from zero to apredetermined maximum flow rate.
 11. The machine of claim 1, whereinsaid means for feed liquid to enter said feed liquid region comprises atleast one feed liquid entry port in said base located within the areacircumscribed by said evaporation reactor and at least one tubularextension fit to each of said at least one feed liquid entry port on anupper surface of said base, wherein said extension terminates in saidfeed liquid region, and whereby such arrangement allows the feed liquidto remain substantially separated from the liquid concentrate.
 12. Themachine of claim 11, further including a feed liquid tank, wherein saidfeed liquid entry port is hydraulically connected to said feed liquidtank, said feed liquid tank located such that a predetermined liquidsurface operating level is maintained within said tubular evaporationreactor by gravity flow.
 13. The machine of claim 1, wherein said meansfor vapor to exit comprises a vapor exit port in said cap structure anda vapor conduit hydraulically connected to said vapor exit port.
 14. Themachine of claim 1, wherein said means for vapor to exit comprises avapor exit in said base and a vapor conduit hydraulically connected tosaid vapor exit port, said vapor conduit extending upwards to a pointabove the liquid surface inside said evaporation reactor.
 15. A machinefor evaporating liquids, comprising: (a) a substantially vertical,tubular evaporation reactor adapted to provide a liquid concentrateregion below a feed liquid region, wherein said evaporation reactorcomprises an outer tube and an inner tube of smaller outside dimensionrelative to said outer tube located concentrically within said outertube, whereby said outer tube and said inner tube form a longitudinalannulus adapted for a feed liquid to react with solar radiation, (b) abase located at a lower end of said evaporation reactor, (c) a capstructure located at an upper end of said evaporation reactor, (d) atleast one feed liquid opening in said base located within the areacircumscribed by said evaporation reactor and a tubular extension fit toeach said feed liquid opening on an upper surface of said base, saidextension terminating in said feed liquid region, whereby sucharrangement allows the feed liquid to remain substantially separatedfrom the liquid concentrate, (e) at least one concentrate opening insaid base located within the area circumscribed by said evaporationreactor, said concentrate opening adapted to act as a passageway forliquid concentrate to exit said evaporation reactor, (f) at least onevapor opening in said cap structure, said base, or both, and a vaporconduit hydraulically connected to said vapor opening, (g) at least onerod, affixed to and extending from said base to said cap structure, saidrod affixed to said cap structure, said rod adapted to be put in tensionwhereby said evaporation reactor is in compression, thereby creatingsubstantially watertight seals between said base, said evaporationreactor, and said cap structure, (h) a feed liquid tank, wherein saidfeed liquid opening is hydraulically connected to said feed liquid tank,said feed liquid tank located such that a predetermined liquid surfaceoperating level is maintained within said tubular evaporation reactor bygravity flow, and (i) a liquid concentrate metering device, wherein saidliquid concentrate opening is hydraulically connected to said meteringdevice to regulate concentrate flow from zero to a predetermined maximumflow rate.
 16. A method for creating distilled liquid from contaminatedliquids using solar radiation, comprising: (a) providing a machine ofthe type comprising a substantially vertical, tubular evaporationreactor adapted to provide a liquid concentrate region below a feedliquid region, a base located at a lower end of said evaporationreactor, a cap structure located at an upper end of said evaporationreactor, a means for feed liquid to enter said feed liquid region withinsaid evaporation reactor, a means for liquid concentrate to exit saidevaporation reactor from said liquid concentrate region, a means forvapor to exit said evaporation reactor, at least one tension member thatconnects said base to said cap structure and acts to compress saidevaporation reactor between said base and said cap structure, therebycreating substantially watertight seals between said base, saidevaporation reactor, and said cap structure, (b) providing at least onesolar reflector device located congruently with said evaporation reactorso as to direct reflected solar radiation to a point or line coincidentwith said evaporation reactor, (c) introducing feed liquid into saidevaporation reactor, and (d) drawing off distillate.
 17. The method ofclaim 16, further comprising: (a) recovering, with a suitable heatexchanger, heat lost through condensation of said vapor and/or heattransported with the concentrate, and (b) using said recovered heat topreheat the feed liquid.
 18. A machine for evaporating liquids,comprising: (a) a substantially vertical, tubular evaporation reactoradapted to provide a liquid concentrate region below a feed liquidregion, (b) a base located at a lower end of said evaporation reactor,(c) a cap structure located at an upper end of said evaporation reactor,(d) at least one feed liquid opening in said base located within thearea circumscribed by said evaporation reactor and at least one tubularextension fit to each of said at least one feed liquid opening on anupper surface of said base, wherein said extension terminates in saidfeed liquid region, and whereby such arrangement allows the feed liquidto remain substantially separated from the liquid concentrate, (e) atleast one concentrate opening in said base located within the areacircumscribed by said evaporation reactor, said concentrate openingadapted to act as a passageway for liquid concentrate to exit saidevaporation reactor, (f) at least one vapor opening in said capstructure, in said base, or both and at least one vapor conduithydraulically connected to said vapor opening, (g) at least one tensionmember that connects said base to said cap structure and acts tocompress said evaporation reactor between said base and said capstructure, thereby creating substantially watertight seals between saidbase, said evaporation reactor, and said cap structure.
 19. The machineof claim 18, further including at least one solar reflector devicelocated in relation to said evaporation reactor so as to directreflected solar radiation to a point or line coincident with saidevaporation reactor.
 20. The machine of claim 18 wherein saidevaporation reactor comprises an outer tube and an inner tube of smalleroutside dimension relative to said outer tube located concentricallywithin said outer tube, whereby said outer tube and said inner tube forma longitudinal annulus adapted for a feed liquid to react with solarradiation.
 21. The machine of claim 20 wherein said outer tube issubstantially transparent, further including small diameter wireembedded within and/or affixed to the surface of said outer tube. 22.The machine of claim 20 wherein said inner tube and/or said outer tubeis tinted blue-green to resemble the color of water in the ocean. 23.The machine of claim 18 wherein said tension member comprises at leastone rod, affixed to and extending from said base to said cap structure,said rod affixed to said cap structure, said rod adapted to be put intension whereby said evaporation reactor is in compression.
 24. Themachine of claim 18 wherein said tension member comprises at least oneflexible, elastic member secured to said base and to said cap structure,said elastic member adapted to act in tension to compress saidevaporation reactor between said base and said cap structure.
 25. Themachine of claim 18 wherein said evaporation reactor comprises asubstantially transparent outer tube and said tension member comprisesat least one rod extending from said base to said cap structure, saidrod adapted to act in tension to compress said evaporation reactorbetween said base and said cap structure.
 26. The machine of claim 18,further including a liquid concentrate metering device, wherein saidliquid concentrate opening is hydraulically connected to said meteringdevice to regulate concentrate flow from zero to a predetermined maximumflow rate.
 27. The machine of claim 18, further including a feed liquidtank, wherein said feed liquid opening is hydraulically connected tosaid feed liquid tank, said feed liquid tank located such that apredetermined liquid surface operating level is maintained within saidtubular evaporation reactor by gravity flow.